Semiconductor manufacturing technologies continue to evolve in order to provide memory devices having increasingly higher storage capacity, integration density, and response speed. Dynamic random access memory (DRAM) devices are most widely used as memory for electric and electronic apparatuses because such devices can have high storage capacity and integration density. A DRAM device memory cell typically includes one access transistor and one storage capacitor.
As the integration density of a DRAM device memory cell increases, the memory cell generally occupies less area on a semiconductor substrate. With less area, capacitors in the memory cells can need higher capacitance characteristics.
The capacitance of a capacitor can be increased by using a dielectric material that has a higher dielectric constant as a dielectric layer in the capacitor, or the surface area of the capacitor can be increased. Some high dielectric material that have been considered for use in the dielectric layer of the capacitor include Al2O3, Ta2O5, or HfO2. However, forming a capacitor with a high dielectric material in a dielectric layer can be complex because of process variations that can occur during manufacturing. To increase the surface area of a capacitor, stacked, trench, and cylindrical type capacitors have been substituted for planar type capacitors.
In the DRAM device, the capacitors should be electrically connected to source/drain regions of a semiconductor substrate. Consequently, the locations of the capacitors are limited by the locations of the source/drain regions. When the spacing between adjacent capacitors becomes narrow, an electrical short between capacitors may occur more frequently. A landing pad electrode can be formed on a storage node contact to increase the spacing between adjacent capacitors. However, additional processes that include deposition process and photolithography process can be needed to form the landing pad electrodes. Moreover, a very small photoresist pattern may need to be formed to form the landing pad electrode. An argon fluoride laser having a relatively short wavelength may be used in the photolithography process with the photoresist pattern, however the associated manufacturing cost may thereby increase.
As the integration degree of memory cells in the DRAM devices increases, the separation between contacts and other wirings can become narrower and the resulting parasitic capacitance therebetween can increase. Increased parasitic capacitance can cause increased operation failures and deterioration of the operating speed of the DRAM devices.